Plumbing Leak - ? Where??

I live in a 2 story colonial. 7 Years ago, water came through the kitchen ceiling (which, unfortunately was drywalled and then covered with 12" x 12" tiles).

Plumber tore out the ceiling, long and short, didn't find any leak. Recommended caulking and shower doors, which we did. Following no leak, we repaired ceiling and reinstalled ceiling tiles

Now, just noticed spot on kitchen ceiling - different area, but still under bathroom. Now closer to wall of house (directly under bathroom sinks, vanity).

Ceiling tiles are saturated along the side of the wall (3 tiles). I don't even know who to call to pursue repair of this problem. Assuming ceiling will need to be torn out again - isn't there an easier way? Could be sink plumbing, toilet, shower?? I know water travels!! HELP!

First things I would check would be:

Shutoffs at the wall, lav and toilet.
P-trap at the lav
leaks from toilets
leaks around shower valves, doors and walls.

And yes, water can and does travel, that part sucks.

leak

Is this a stall shower or a bath tub with a shower?

The unfortunate thing is, once drywall is soaked, it's ruined and has to be taken out. A relatively small leak like this is darned hard to find. It would be a whole bunch easier if it was a pipe spraying water under pressure. As it is, it could be all of the things already mentioned as well as a leak in a drain pipe joint. There's no quick, easy solution, I'd take the ceiling out, clean everything up there, then try to make the leak happen. A strong flashlight is very helpful. Troubleshooting to find the leak is the hard part, fixing it is easy after you find it. The mess and etc. is a PITA.

leak

There is no logic by starting the way your plumber did.
I'll just assume that this is the sliding doors on your bath tub we're talking about.
Before I would start cutting any holes in the ceiling, I would do a process of elimination.
Let things dry for a couple of days.
Do you have an access door for the bath tub?
If you do take a good extension light and look in the access for water marks.
That might lead you somewhere.

Do you have an access????????
Let me know, we can go on from there........